BEIJING - China on Wednesday refuted allegations of hacking activities as groundless, calling for international cooperation to fight cyber crime rather than criticize each other in an irresponsible way.

Foreign Ministry spokesman Hong Lei made the remarks at a regular press briefing, noting that groundless criticism is "irresponsible and unprofessional, which will not help to solve the problem".

US cyber security firm Mandiant on Monday released a report which alleged that a secret Chinese military unit in Shanghai was behind years of cyber attacks against US companies.

"Firmly opposing cyber attacks, China has established relevant laws and regulations to crack down on hacking," Hong said.

China has been a major victim of cyber attacks, most of which are from the United States, according to Hong.

He said China and the United States have maintained communication over the issue, adding that as cyber crime is an international problem, it should be solved through international cooperation on the basis of mutual trust and respect.

Earlier on Wednesday, China's military spokesman also said the country's armed forces had never backed any hacking activities, denouncing US cyber security firm Mandiant's report as groundless both in facts and legal basis.

It was groundless in fact because it came to the conclusion that the source of attack came from China simply because of the discovery that attacks were linked to IP addresses based in China, Geng Yansheng, spokesman for the Ministry of National Defense, said at a briefing.

Firstly, as known to all, it is common for hacking attacks on the Internet to take place by peculating IP addresses that "it happens almost everyday," according to the spokesman.

Secondly, there has been no clear and consistent definition of cyber attacks around the world. The report lacks legal basis to assert cyber espionage only by cataloguing some routine cyber activities, he said.

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